Problem: Which of these numbers is composite? ${3,\ 19,\ 37,\ 75,\ 97}$
A composite number is a number that has more than two factors (including 1 and itself). 3, 19, 37, and 97 each have only two factors. The factors of 75 are 1, 3, 5, 15, 25, and 75. Thus, 75 is the composite number.